Dynamic Contrast‐Enhanced MRI in the Evaluation of Carotid Space Paraganglioma versus Schwannoma

<jats:title>ABSTRACT</jats:title><jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>To describe the potential role of dynamic contrast‐enhanced (DCE) MRI in differentiating carotid space (CS) paraganglioma from schwannoma in the head and neck.</jats:p></jats:sec><jats:sec><jats:title>MATERIAL AND METHODS</jats:title><jats:p>We retrospectively reviewed records of 126 patients who had undergone DCE‐MRI between June 2008 and July 2014 and found six patients with histologically verified benign CS tumors. The images were evaluated for tumor T1 and T2 signal characteristics, flow voids, and enhancement pattern. The dynamic data were analyzed for quantitative parameters using extended Toft's model (<jats:italic>K<jats:sub>trans</jats:sub></jats:italic>, <jats:italic>K<jats:sub>ep</jats:sub></jats:italic>, <jats:italic>V<jats:sub>e</jats:sub></jats:italic>, and <jats:italic>V<jats:sub>p</jats:sub></jats:italic>) and semiquantitative parameters based on time–intensity curve (area under curve, peak enhancement, wash‐in, wash‐out, signal‐enhancement ratio [SER], and time for maximum enhancement [TME]). Due to the small sample size, groups were compared qualitatively.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Patients with CS paraganglioma (P group, <jats:italic>n</jats:italic> = 2) and schwannoma (S group, <jats:italic>n</jats:italic> = 4) were included. All tumors were hypointense on T1W imaging, hyperintense on T2W imaging, and show avid enhancement. One patient with paraganglioma had subtle flow voids. The conventional MR images were insufficient to confidently diagnose tumor type.</jats:p><jats:p>Both paragangliomas had high peak enhancement and SER, and a short TME, while the schwannomas had relatively low peak enhancement and SER with a longer TME. <jats:italic>K<jats:sub>trans</jats:sub></jats:italic><jats:sub>,</jats:sub> <jats:italic>K<jats:sub>ep</jats:sub></jats:italic>, and <jats:italic>V<jats:sub>e</jats:sub></jats:italic> were relatively low in the paragangliomas than in the schwannomas.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSION</jats:title><jats:p>DCE‐MRI could potentially be used to assist differentiating paraganglioma from schwannoma, when diagnosis is difficult on the conventional MR imaging sequences. Simple assessment of semiquantitative parameters suffices to provide supportive information.</jats:p></jats:sec>